1. Field of the Invention
The present invention relates to compression latches for doors or panels.
2. Brief Description of the Prior Art
Compression latches for mounting on doors or panels are known. Compression latches are used in applications in which it is desirable to both latch a door or panel to the frame in which it is mounted and to seal the edge of the panel to the frame when closed. For example, compression latches are desirable when the opening in which the panel is mounted is provided with a gasket that must be compressed to provide a seal.
Examples of compression latches are provided in the Southco Handbook 2000 (Southco, Inc., Concordville, Pa.) at pages 23-69.
Fixed compression latches provide a consistent, pre-set compression while adjustable compression latches provide flexibility in setting the amount of compression.
Compression latches often include a pawl designed to engage the frame inside the enclosure to latch the panel shut. Since the compression latch must be operated from outside the enclosure, there must be a mechanism linking the portion of the latch operated by the user with the pawl positioned inside the enclosure. Further, often the latch mechanism, or at least a substantial portion thereof, protrudes through an aperture in the panel. The latch mechanism itself can reduce the volume of the sealed interior that would otherwise available.
In some applications, such as cabinets for radio transmitters and telephone equipment for outdoor use, the enclosure preferably remains well sealed against the environment, to avoid environmental stresses penetrating into the enclosure and to avoid EMI leakage from equipment to the environment. Thus, in such applications, the latch mounting aperture and the latch itself may present routes between the interior of the enclosure and the exterior, undesirably reducing the degree of isolation of the enclosure from the environment.
There is a continuing need for a simple, easy to install compression latch that provides suitable compression force and yet reduces the extent to which the environmental isolation of the enclosure is compromised by installation and use of the latch.
There is also a continuing need for a compression latch that provides a minimal xe2x80x9cfootprintxe2x80x9d inside the cabinet on which the compression latch is installed.
The present invention provides a simple linear compression latch that can be easily and securely mounted on the outside of a door or panel. The linear compression latch of the present invention provides a consistent, pre-set compression. At the same time, only a small portion of the latch mechanism protrudes into the interior of the enclosure, so that the cabinet is easy to seal against the environment. The linear compression latch of the present invention is simple to manufacture, assemble and install, and is preferably assembled from less than a dozen parts.
Since most of the latch mechanism is located outside the enclosure, the linear compression latch of the present invention takes up a minimum of useable space within the enclosure, thus minimizing or eliminating the space previously used by other types of compression latches inside the sealed area of a cabinet. The linear compression latch of the present invention provides a single-point compression between a door and a frame.
The compression is provided by a pawl, which moves toward the door as the handle of the latch is closed. The pawl moves by xe2x80x9clinear motionxe2x80x9d meaning that it moves substantially only in the plane parallel to the surface of the door. To open the linear compression latch, a lever is pulled upward, away from the latch. This causes the pawl to initially move away from the door frame, and then to withdraw from under the door frame to a position under the door so that the door can be opened. Overall, the pawl moves in an xe2x80x9cLxe2x80x9d-shaped motion.
The linear compression latch includes a housing and a lever mounted in the housing and rotatable by an operator between a first position and a second position. The latch also includes a pawl mounted for substantially linear motion. The pawl is actuated by rotation of the lever, travels substantially linearly between an open position to a closed position as the lever is rotated between the first position to second position. Preferably, the pawl is mounted to travel between the open position along a first path and an intermediate position, and then to travel in a second path in a direction substantially perpendicular to the first path between the intermediate position and the closed position. For example, when the latch is being opened, the pawl initially travels downward along a substantially linear path from a first position to an intermediate position, then it travels in a second linear path away from the door frame from the intermediate position to the second position in which the entire pawl is positioned under the door, the latch is fully open, and the door can be opened.
Preferably, the linear compression latch also comprises a carriage that is mounted for linear motion within the housing. In this case the pawl is mounted within the carriage, and the carriage is displaced with the pawl as the pawl travels along the first path. In the closed position the pawl presses upward against the underside of the door frame to compress a gasket between the door and the door frame. When the latch is opened, the pawl and the carriage initially travel downward away from the door frame to release the compression on the gasket. Preferably, the latch also includes a link means for linking the lever and the pawl. Preferably, the link means is rotatably affixed to both one of the arms of the lever and rotatably affixed to the pawl as well. Preferably, connection means, such as a cylindrical pin, are provided to rotatably connect the link means and the pawl. It is also preferred that the connection means also rotatably connects the pawl and the carriage. Further, it is preferred that the lever have a first arm and a second arm that are not collinear, and instead orient at an angle less than 180 degrees to each other.
It is thus an object of the present invention to provide a compression latch having a substantially linear motion.
It is also an object of the present invention to provide a compression latch having a mechanism which is located substantially outside the enclosure on which the compression latch is mounted.
It is a further object of the present invention to provide a compression latch that can be easily and effectively sealed.
It is a further object of the present invention to provide a compression latch of a design that reduces the need to provide a seal for the latch itself when used in an enclosure that it preferably isolated from its environment.
These and other objects of the invention will become apparent through the following description and claims.